Thermodynamic properties

The thermodynamic properties are calculated using the NASA polynomials (7 coefficient fit). The library module that reads the NASA polynomials expect the input file "therm.dat" in the "data" folder by default. The location for the "data" folder is at the same level as that of the "src" folder. The NASA polynomial file can be downloaded from a number of websites. The library lets you calculate the thermochemical data of pure species or for a gas mixture. A skeleton of the NASA polynomial is given below

 H2               TPIS78H   2   00   00   00G   200.000  3500.000   1000.00    1
 3.33727920E+00-4.94024731E-05 4.99456778E-07-1.79566394E-10 2.00255376E-14    2
-9.50158922E+02-3.20502331E+00 2.34433112E+00 7.98052075E-03-1.94781510E-05    3
 2.01572094E-08-7.37611761E-12-9.17935173E+02 6.83010238E-01 8.46810200E+03    4
HO2               L 5/89H   1O   2   00   00G   200.000  3500.000  1000.000    1
 4.01721090E+00 2.23982013E-03-6.33658150E-07 1.14246370E-10-1.07908535E-14    2
 1.11856713E+02 3.78510215E+00 4.30179801E+00-4.74912051E-03 2.11582891E-05    3
-2.42763894E-08 9.29225124E-12 2.94808040E+02 3.71666245E+00 1.00021620E+04    4

Pure species propoerties

The pure species thermodynamic properties are calculated according to the following equations.

Specific heat

The molar specific heat capacity $C_{pk}^0$ (J/mol-K) of a chemical species k is calculated using

\[\frac{C_{pk}^0}{R} = a_{1k} + a_{2k} T_k + a_{3k}T^2 + a_{4k}T^3 + a_{5k} T^4\]

Main.IdealGas.cp — Function

Calculate the specific heat of pure species J/mol-K

Usage-1:

cp(thermo,T)

'thermo::NASAThermo': NASAThermo of the species
'T::Float64': Temperature in K at which the property is required

Usage-2:

cp(sp,T,thermo,ig)

'sp::String' : species name
'T::Float64' : Temperature K
'thermo::SpeciesThermoObj' : Structure of SpeciesThermoObj
'ig::Gasphase ' : Gasphase object

source

Enthalpy

The molar enthalpy $H_{pk}^0$ (J/mol) of a chemical species k is calculated according to

\[\frac{H_k^0}{RT} = a_{1k} + \frac{a_{2k}}{2} T + \frac{a_{3k}}{3}T^2 + \frac{a_{4k}}{4}T^3 + \frac{a_{5k}}{5} T^4 + \frac{a_{6k}}{T}\]

Main.IdealGas.H — Function

H(thermo::NASAThermo, T::Float64) Calculates the enthalpy of pure species J/mol

Usage-1:

H(thermo,T)

'thermo::NASAThermo': NASAThermo of the species
'T::Float64': Temperature in K at which the property is required

Usage-2:

H(sp,T,thermo,ig)

'sp::String' : species name
'T::Float64' : Temperature K
'thermo::SpeciesThermoObj' : Structure of SpeciesThermoObj
'ig::Gasphase ' : Gasphase object

source

Entropy

The molar entropy $S_{pk}^0$ (J/mol-K) of a chemical species kis calculated according to

\[\frac{S_k^0}{R} = a_{1k} \ln T + a_{2k} T + \frac{a_{3k}}{2}T^2 + \frac{a_{4k}}{3}T^3 + \frac{a_{5k}}{4} T^4 + a_{7k}\]

Main.IdealGas.S — Function

S(thermo::NASAThermo, T::Float64) Calculates the entropy of pure species J/mol-K

Usage-1:

S(thermo,T)

'thermo::NASAThermo': NASAThermo of the species
'T::Float64': Temperature in K at which the property is required

Usage-2:

S(sp,T,thermo,ig)

'sp::String' : species name
'T::Float64' : Temperature K
'thermo::SpeciesThermoObj' : Structure of SpeciesThermoObj
'ig::Gasphase ' : Gasphase object

source

Mixture average properties

The mixture average specific heat, enthalpy and entropy may be calculated using the following equations

Specific heat

\[\overline{C}_p = \sum_{k=1}^K C_{pk}X_k\]

Main.IdealGas.cpmix — Function

Calculates the specific heat of a mixture in J/mol-K

Usage

cpmix(td,T,mlf)

'thermoObj::SpeciesThermoObj' : Structure of SpeciesThermoObj
'T::Float64' : Temperature in K
'mlf::Array{Float64,1}' : species mole fractions

source

Enthalpy

\[\overline{H} = \sum_{k=1}^K H_kX_k\]

IdealGas.hmix

Entropy

\[\overline{S} = \sum_{k=1}^K \bigg(S_k^0 -R\ln X_k - R\ln(p/P_\mathrm{atm}) \bigg)X_k.\]

Gibb's free energy

\[\overline{G} = \sum_{k=1}^K \bigg[ H_k - T_k\bigg(S_k^0 -R\ln X_k - R\ln(p/P_\mathrm{atm}) \bigg) \bigg]X_k\]